It is a point of contention if Google should optimize for saving time for the individual user, (using data only available to that user), or for that user (but using routing information of other google users), or for all users on average (but potentially to the detriment of some users to give other users a bigger advantage), or for the public on average (ie. routing cars to reduce traffic, but possibly putting google users at a disadvantage compared to non-google users).

Various cities round the world have different optimization goals as they try out different approaches.